Any discussion of the related art throughout this specification should in no way be considered as an admission that such art is widely known or forms part of the common general knowledge in the field.
Nanotube fabric layers and films are used in a plurality of electronic structures, and devices. For example, U.S. Pat. No. 8,217,490 to Bertin et al., incorporated herein by reference in its entirety, teaches methods of using nanotube fabric layers to realize nonvolatile devices such as, but not limited to, block switches, programmable resistive elements, and programmable logic devices. U.S. Pat. No. 7,365,632 to Bertin et al., incorporated herein by reference, teaches the use of such fabric layers and films within the fabrication of thin film nanotube based resistors. U.S. Pat. No. 7,927,992 to Ward et al., incorporated herein by reference in its entirety, teaches the use of such nanotube fabrics and films to form heat transfer elements within electronic devices and systems.
Through a variety of previously known techniques (described in more detail within the incorporated references) nanotube elements can be rendered conducting, non-conducting, or semi-conducting before or after the formation of a nanotube fabric layer or film, allowing such nanotube fabric layers and films to serve a plurality of functions within an electronic device or system. Further, in some cases the electrical conductivity of a nanotube fabric layer or film can be adjusted between two or more non-volatile states as taught in U.S. Pat. No. 7,781,862 to Bertin et al., incorporated herein by reference in its entirety, allowing for such nanotube fabric layers and films to be used as memory or logic elements within an electronic system.
U.S. Pat. No. 7,335,395 to Ward et al., incorporated herein by reference in its entirety, teaches a plurality of methods for forming nanotube fabric layers and films on a substrate element using preformed nanotubes. The methods include, but are not limited to, spin coating (wherein a solution of nanotubes is deposited on a substrate which is then spun to evenly distribute said solution across the surface of said substrate), spray coating (wherein a plurality of nanotubes are suspended within an aerosol solution which is then dispersed over a substrate), and dip coating (wherein a plurality of nanotubes are suspended in a solution and a substrate element is lowered into the solution and then removed). Further, U.S. Pat. No. 7,375,369 to Sen et al., incorporated herein by reference in its entirety, and U.S. Pat. No. 7,666,382 to Ghenciu et al., incorporated herein by reference in its entirety, teach nanotube solutions well suited for forming a nanotube fabric layer over a substrate element via a spin coating process.
Typically, solutions made from raw nanotubes cannot be used in a semiconductor fabrication plant, because raw nanotubes may contain undesirable impurities, such as amorphous carbon, metal, etc., which would negatively impact the electrical properties of the nanotube film or fabric fabricated therefrom. Accordingly, raw nanotubes—and application solutions thereof—have to be purified and/or processed before use.